1. Field of the Invention
The present invention relates to a scintillator panel and a radiation image sensor which are used for medical X-ray photography and the like, and methods of making them.
2. Related Background Art
While X-ray sensitive films have been used in medical and industrial X-ray photography, radiation imaging systems using radiation detecting devices have been coming into wider use from the viewpoint of convenience and their storability of photographed results. In such a radiation imaging system, pixel data caused by two-dimensional radiation are acquired by a radiation detecting device as an electric signal, which is then processed by a processing unit, so as to be displayed onto a monitor.
Conventionally known typical radiation detecting devices include those disclosed in Japanese Patent Application Laid-Open No. HEI 5-196742 and No. SHO 63-215987. Such a radiation detecting device forms a scintillator on an imaging device or a fiber optical plate (FOP), i.e., an optical part constituted by a plurality of optical fibers bundled together, such that the radiation incident thereon from the scintillator side is converted by the scintillator into light, so as to be detected.
Here, CsI, which is a typical scintillator material, is high in moisture absorbency and deliquesces by absorbing vapor (moisture) in the air, thereby deteriorating characteristics of the scintillator such as the resolution in particular. Therefore, a moisture-resistant barrier impermeable to water is formed on the upper side of the scintillator layer in the above-mentioned radiation detecting device, so as to protect the scintillator against the moisture.
As radiation detecting devices are in wider use, there are cases where it is desirable to use a radiation detecting device having a structure in which a scintillator is formed not on an imaging device or FOP but on a substrate having a favorable X-ray transmissivity such as a substrate made of Al, while the imaging device is disposed so as to face the scintillator.
In such a case, since X-rays are incident from the substrate side, a metal film aimed at moisture resistance cannot be formed on the surface of scintillator, and the moisture resistance has been problematic when a transparent organic film is simply formed on the surface of scintillator for the purpose of moisture resistance.
It is an object of the present invention to provide a scintillator panel and a radiation image sensor which are excellent in moisture resistance, and methods of making them.
The scintillator panel of the present invention is characterized in that it comprises a radiation-transparent substrate, a scintillator formed on the substrate, a first transparent organic film covering over the scintillator, and a transparent inorganic film formed on the first transparent organic film. According to the present invention the transparent inorganic film is formed on the first transparent organic film covering over the scintillator, the moisture resistance of scintillator can remarkably be improved by the transparent inorganic film.
The radiation image sensor of the present invention is characterized in that it comprises a radiation-transparent substrate, a scintillator formed on the substrate, a first transparent organic film covering over the scintillator, a transparent inorganic film formed on the first transparent organic film, and an imaging device disposed so as to face the scintillator. According to the present invention the transparent inorganic film is formed on the first transparent organic film covering over the scintillator, the moisture resistance of scintillator can remarkably be improved by the transparent inorganic film.
The method of making the scintillator panel of the present invention is characterized in that it comprises steps of forming a scintillator on a radiation-transparent substrate, forming a first transparent organic film covering over the scintillator, and forming a transparent inorganic film on the first transparent organic film. Since the transparent inorganic film is formed on the first transparent organic film, the present invention can make a scintillator panel in which the moisture resistance of scintillator is remarkably improved.
The method of making an image sensor according to the present invention is characterized in that it comprises steps of forming a scintillator on a radiation-transparent substrate, forming a first transparent organic film covering over the scintillator, forming a transparent inorganic film on the first transparent organic film, and disposing an imaging device opposite the scintillator. Since the transparent inorganic film is formed on the first transparent organic film, the present invention can make a radiation image sensor in which the moisture resistance of scintillator is remarkably improved.
The scintillator panel according to the present invention may further comprise a second transparent organic film formed on the transparent inorganic film of the scintillator panel. Since the second transparent organic film is formed on the transparent inorganic film, the present invention can prevent the transparent inorganic film from peeling.
The transparent inorganic film may be formed by a material including a substance selected from the group consisting of SiO2, Al2O3, TiO2, In2O3, SnO2, MgO, SiN, MgF2, LiF, CaF2, AgCl, and SiNO.
The first transparent organic film may cover all over the substrate for securely protecting the scintillator from moisture.
The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not to be considered as limiting the present invention.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.